1. Field of the Invention
The present invention relates to a driving machine, more particularly, to a driving machine for driving staples having a nearly U-shape.
2. Description of the Related Art
Conventionally, a driving machine for driving staples having a nearly U-shape is known as a kind of driving machine. In this kind of driving machine, a magazine loaded with a bundle of multiple staples bonded with an adhesive or the like is mounted in the nose section thereof incorporating a sliding driver blade. A feeder for urging the bundle of staples toward the nose section is provided inside this magazine. The bundle of staples is urged using the feeder and pushed into a launching passage through which the driver blade inside the nose section passes, and the staple located at the leading end in the urging direction is driven using the driver blade.
For this kind of driving machine, various empty driving prevention apparatuses have been proposed to prevent the so-called empty driving in which the driver blade is activated and strikes the feeder after the staple at the trailing end in the urging direction has been driven. As an example of this empty driving prevention apparatus, as disclosed in JP-H06-297353-A, an apparatus is known that is provided with a switch that makes contact with the feeder and turns ON for the first time when the staple at the trailing end has been driven and the feeder has moved further in the urging direction, and the apparatus is configured such that the movement of the driver blade is restricted when this switch is ON. For the purpose of securely obtaining the movement amount of the feeder when the staple at the trailing end has been driven and the feeder has moved further in the urging direction, the apparatus is configured such that a convex section is provided at the position where the feeder makes contact with and urges the staple, such that a concave section that is engaged with the convex section is provided on the face making contact with the urged staple inside the launching passage, and such that after the staple at the trailing end has been driven, the feeder moves and the convex section is inserted into the concave section.
In the conventional driving machine, the movement amount of the feeder after the staples have been driven is obtained by virtue of the convex section of the feeder and the concave section inside the launching passage, whereby empty driving of the driver blade is prevented securely. However, since the inside of the launching passage is a place where the staple passes through and the concave section is formed in this place, there is a danger that part of the staple may be caught and the staple may jam inside the launching passage. In particular, when the staple is struck using the driver blade, a buckling stress is generated in the staple in the state that the tip ends of the staple make contact with a driven member. If the position of the end section of the staple on the side of the driver blade is coincident with the position of the concave section inside the launching passage at this time, the end section may buckle and enter the concave section, and there is a danger that improper staple driving may occur. Hence, an object of the present invention is to provide a driving machine capable of preventing jamming of fasteners to reduce improper driving.